1. Field of the Invention
The present invention is related to an omni-directional broadband helical antenna array, and especially to an antenna array which is suitable to be mounted in a communication instrument to form better omni-directional signal receiving and emitting functions under a complicated interior environment.
2. Description of the Prior Art
Coils used as signal receiving and emitting elements are well known, such coils can get their functions of various antennae by selecting related factors such as material, diameters, coil pitches and lengths. Modern communication instruments which most widely and popularly use helical antennae are mobile phones.
Such helical antennae available presently are mostly exposed. In other words, the helical antennae are mostly exposed to the outside of instruments; when in receiving and emitting signals, there is almost no impedance or influence. However, modern communication instruments carried on one""s own such as notebook style computers also have communication functions and need antenna devices. Such built-in antennae in notebook style computers will have their signal receiving and emitting functions influenced by the complicated interior environments. For example, they may have no other electronic elements at one side thereof and can have desired signal receiving and emitting functions, but they may have electronic elements at the other side thereof and signal receiving and emitting functions thereof can be seriously influenced and gotten lost.
Although various microstrip antennae have been developed in the recent years, such as those disclosed in the U.S. Pat. No. 392,177 and 381,018, for improvement in getting rid of the impedance and deficient in using the antennae, such earlier microstrip antennae generally only suit narrower bandwidths. U.S. Pat. No. 07/695686 provides a preferred helical microstrip antenna which can solve the problems in the earlier microstrip antennae. However, such a helical microstrip antenna does not meet the requirement of ordinary miniaturized electronic equipment by virtue that the diameter of the antenna will be quite enlarged when in the condition of low frequency.
The object of the present invention is to provide an omni-directional broadband helical antenna array especially suitable for mounting in the interior of communication instruments, in order to provide better omni-directional signal receiving and emitting functions under the complicated interior environment.
To get the above stated object, the present invention provides on the four corners of a square electric circuit board each with a helical antenna. The helical antennae feed signals outwardly via microstrip lines, and they feed signals outwardly via another microstrip line after gathering the above mentioned microstrip lines. Thereby, the helical antenna array can form an omni-directional broadband receiving and emitting device.
The above stated helical antennae can separate the array into a plurality of sections with reflector such as copper sheets to increase the gain of the antennae.
To prevent disturbance among the antenna, distances between every two helical antennae had better be in the range of 0.25 xcex-0.3 xcex; while the length of the microstrip line as an impedance converter is about xc2xc xcex.
The present invention will be apparent in its novelty and other characteristics after reading the detailed description of the preferred embodiment thereof in reference to the accompanying drawings. Wherein: